The Swordsman's Heir
An aging swordmaster named Bokuden was laying in bed with the question of which of his three sons would become his principal heir and inherit the chief instructor status of his school of swordsmanship. Bokuden devised the following test: He placed a wooden board above the sliding door to his room, balancing it so that it would fall as soon as anyone entered the room. He then summoned each of his sons in turn.
Prior to entering the room, the first son immediately sensed something was amiss. He cautiously opened the sliding door, extended his hand and caught the board when it fell. The second son barged right into the room but managed to dodge the falling board. The third son also went straight into the room but he was able to draw his sword and cleave the board into two pieces as it fell midair. After observing their behavior, Bokuden made the first son his successor.